Glossary term: Ring

Description: The four giant planets in our Solar System (Jupiter, Saturn, Uranus, and Neptune) – for exoplanets, we cannot yet tell – are surrounded by numerous small pieces of ice or rock, micrometers to meters in size, in the shape of large rings. The most spectacular rings are those surrounding Saturn: An intricate system of rings separated by gaps. Some of that structure comes about through interaction with Saturn's larger moons, and two gaps are opened up by tiny moons orbiting inside them. There are several hypotheses about how the rings formed, most of them involving a moon torn apart or stripped through Saturn's gravity. There are estimates that Saturn's rings will have dissolved in a few 100 million years – not a very long time by astronomical standards. Jupiter, Uranus, and Neptune have less pronounced ring systems.

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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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The planet Saturn with pale brownish cloud ribbons and its thin and extended greyish rings


Caption: The NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 observed Saturn on 20 June 2019 as the planet made its closest approach to Earth this year, at approximately 1.36 billion kilometres away. The image shows coloured bands of gas on the planet's surface as well as its prominent rings made of ice and rocky material.
Credit: NASA, ESA, A. Simon (Goddard Space Flight Center), and M.H. Wong (University of California, Berkeley) credit link

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

Uranus appears as a light blue disk with and a pale polar region. Thin white rings surround the planet

Uranus with rings

Caption: The NASA/ESA Hubble Space Telescope’s ACS/HRC camera observed Uranus in August 2005. The surface depicts white clouds and a bright polar region. The rings around Uranus are narrow and contain rocky material from tiny dust particles up to metre-sized boulders.
Credit: NASA, ESA, and M. Showalter (SETI Institute) credit link

License: PD Public Domain icons